Improvement in the manufacture of parchment-paper



UNITED STATES PATENT OFFICE.

ALEXANDER J. SHELDON, OF BUFFALO, NE\V YORK, ASSIGNOR TO COLIN CAMPBELL, OF SAME PLACE.

IMPROVEMENT IN THE MANUFACTURE PARCHMENT-PAPER.

- Specification forming part of Letters Patent No. 99,248. dated January 25, 1e70,

To all whom it may concern:

Be it known that I, ALEXANDER J. SHEL- DON, of the city of Buffalo, in the county of Erie and State .of New York, have invented I the article to determine the requisite strength and temperature of the acid, the length of time the paper is subjected to its influence, and the temperature of the room in which the process is carried on. If the acid is not sufficiently diluted, the material will be charred. If the solution is too weak and the paper is left too long in it, the latter will be partially converted into dextrine. This parchment or membrane, after ithas become wet and subsequently dried, loses, to a great degree, its pliancy, becoming hard and stiff. Various attempts have been made to overcome this defect, and to render the article impervious to water. One process, which has recently been patented, con sists in passing the material, after it has been treated with the diluted acid and the latter removed, through a glycerine bath. Owing to the facility with which glycerine combines with water, this process has failed to accomplish the desired result, the water dissolving and extracting the glycerine from the paper when immersed therein. I have found by experiment that thoroughly-dried paper immersed in pure sulphuric acid is not so immediately affected by the acid as when the latter is slightly diluted. This more instantaneous action of the dilute acid, I have attributed to pores of the paper or comes in more intimatecontact therewith, the water serving as'a vehicle or conductor for the acid, the oily nature of which in a pure state prevents its instantaneous absorption by the paper. The result of my experiments has led to the conclusion that the best effects in the conversion of paper into membrane are .produced by the instantaneous action of the strongest acid, and that this effect is best accomplished by-dipping the paper into pure acid, and then immersing it in a vat of water, the desired change taking place at the moment the acid and water combine, while the quantity of the water so dilutes the acid as to immediately arrest further action on the material thus transformed.

My invention therefore consists, first, in passing papersized, unsized, printed, or otherwisethrough abath of pure commercial sulphuric acid or oil of vitriol, and then immediately into a water bath, whereby I am enabled to produce a superior article. of paper, which possesses the qualities hereinafter enumerated; second, in passing the paper through an alum bath, preparatory to treating it with acid, for protecting it from the undue action of the acid.

In the preparatory alum treatment the paper is simply passed through a bath of alum in solution, and then thoroughly dried,when it is ready for the acid. It may be subjected to the acid treatment during the manufacture of the paper, with or without the previous alum treatment, according to the texture and structure of the paper, by allowing the web,

after it passes the drying-rollers, to dip into a tub of the acid, and thence into the vat containing the water. The process I have employed in experimenting is to dip the pieces of paper to be treated in the vessel containing the acid, and then drop them into a vat of water. The paper is then treated in an alkaline bath in the usual manner, for removing any traces of acid that may remain therein. The material thus produced will be found to possess all of the desired qualities of vegetable parchment, besides the following additional one, viz: It is less pervious to air and water. It can be washed, boiled in hot water, twisted, and otherwise handled in a way that would destroy the ordinary kinds of paper, without injury, becoming, when dried, soft, smooth, and pliable, as at first.

\Vritten and printed paper can be subjected to treatment by my improved process without affecting the elearncss and distinctness of the letters.

Paper treated as before described is better adapted for printing and writing purposes, as

it has a better surface and receives the ink more freely.

Another of the advantages of my improved process is the greatly-reduced cost at which the prepared paper can be produced, which is owing to the fact that no delicate manipulation is required, as in the old process, the acid and water being used in a cold state, and the room in which the process is carried on being of any ordinary temperature comfortable to the operators.

Another characteristic of my improved paper is the facility with which it can be manufactured into sheets and belts of any required thickness, all that is requisite being the immersing of the separate webs in warm water,

and then passing them between press-rolls or otherwise subjecting them to pressure. It is specially adapted for making cuffs, collars,

1. The process of treating paper by passing it through a bath of pure commercial sulphuric acid, and then immediately into a watcr bath, substantially as and for the purpose hereinbefore set forth.

2. The process of passing the paper through an alum bath preparatory to treating it with acid, substantially as hereinbefore described.

ALEXANDER J. SHELDON.

Witnesses:

J AY HYATT, M. A. ROBINSON. 

